Use Regex / Powershell to rename files

Question

How does one rename the following files (New => Old):

filename__Accelerated_C____Practical_Programming_by_Example.chm -> C Practical Programming by Example.chm

filename__Python_Essential_Reference__2nd_Edition_.pdf -> Python Essential Reference 2nd Edition.pdf

filename__Text_Processing_in_Python.chm -> Text Processing in Python.chm

First one should be **Accelerated C++ Practical Programming by Example** imho. — YOU, Apr 07 '11 at 02:44

score 49 · Answer 1 · edited Jul 01 '19 at 21:39

49

Try this one:

Get-ChildItem directory `
        | Rename-Item -NewName { $_.Name -replace '^filename_+','' -replace '_+',' ' }

Note that I just pipe the objects to Rename-Item, it is not really needed to do it via Foreach-Object (alias is %).

Update

I haven't anything documented about the 'magic' with scriptblocks. If I remember correctly, it can be used if the property is ValueFromPipelineByPropertyName=$true:

function x{
    param(
        [Parameter(ValueFromPipeline=$true)]$o,
        [Parameter(ValueFromPipelineByPropertyName=$true)][string]$prefix)
    process {
        write-host $prefix $o
    }
}
gci d:\ | select -fir 10 | x -prefix { $_.LastWriteTime }

edited Jul 01 '19 at 21:39

ΩmegaMan

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answered Apr 07 '11 at 07:14

stej

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1

Woohoo. +1 for eliminating the unnecessary `Foreach` pipeline stage. :-) – Keith Hill Apr 07 '11 at 14:40
hey cool. The docs don't say you could use a scriptblock as a param there. Is this a feature of many other cmdlets? – zdan Apr 07 '11 at 17:19
@zdan, I don't know where it is documented. Maybe found it on a blog. Nobody has answered so far (question on Twitter). See my edited answer. – stej Apr 08 '11 at 08:14

score 34 · Accepted Answer · edited Jun 02 '20 at 22:51

34

This should work:

ls | %{ ren $_ $(($_.name -replace '^filename_+','') -replace '_+',' ') }

Expanding the aliases and naming all argument, for a more verbose but arguably more understandable version, the following is equivalent

Get-ChildItem -Path . | ForEach-Object { Rename-Item -Path $_ -NewName $(($_.Name -replace '^filename_+','') -replace '_+',' ') }

edited Jun 02 '20 at 22:51

LudvigH

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answered Apr 07 '11 at 05:49

zdan

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2

Why using `$` in the second parameter. I found this working too: `ls | % { ren $_ (($_ -replace 'filename_+','') -replace '_+',' ')}` – Emiliano Poggi Apr 07 '11 at 06:42
1

forgot my comment, $ is necessary to cut off last space before the file extension :). Your regex works perfectly! – Emiliano Poggi Apr 07 '11 at 06:49
In case anybody else has the same problem: If, for whatever reason, using the foreach-block results in a "cannot rename because item does not exist" error, try using the script-block as argument to -NewName, as shown in the answer by user @stej (works for me). I cannot understand why this should make any difference. Maybe someone has an idea? – gimpf Feb 26 '16 at 14:38
This answer could be considerably improved if it pointed to some documentation to help beginner readers understand the regex machinery in it. – Owen Feb 20 '22 at 22:04

score 1 · Answer 3 · answered Apr 07 '11 at 01:28

1

Try this out:

$filename = $filename -creplace '_+\.', '.'
$filename = $filename -creplace '_+', ' '

answered Apr 07 '11 at 01:28

ridgerunner

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Use Regex / Powershell to rename files

3 Answers3

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